Influence of silicon on high-temperature (600 °C) chlorosilane interactions with iron

High-temperature (>500 °C) chlorosilane gas streams are prevalent in the manufacture of polycrystalline silicon, the feedstock for silicon-based solar panels and electronics. This study investigated the influence of metallurgical grade silicon on the corrosion behavior of pure iron in these types of environments. The experiment included exposing pure iron samples at 600 °C to a silicon tetrachloride/hydrogen input gas mixture with and without embedding the samples in silicon. The samples in a packed bed of silicon had significantly higher mass gains compared to samples not in a packed bed. Comparison to diffusion studies suggest that the increase in mass gain of embedded samples is due to a higher silicon activity from the gas phase reaction with silicon. The experimental results were supported by chemical equilibrium calculations which showed that more-active trichlorosilane and dichlorosilane species are formed from silicon tetrachloride in silicon packed bed conditions.